The present invention relates to a method and system for automatically inspecting through image processing, a defect or a plurality thereof existing in an electronic circuit wiring pattern such as a printed circuit board pattern, a circuit pattern on a ceramic substrate, a circuit pattern of a hybrid integrated circuit, a circuit pattern of electrodes for facsimile machine, a thin film circuit pattern, a circuit pattern for a liquid crystal display device, a circuit pattern of a large scale integrated circuit and so forth.
There are a variety of conventional systems for the inspection of the external appearance of a circuit pattern. Disclosed in Japanese Patent Application Publication No. 59-24361 is one example, wherein two circuit patterns are compared with each other, and a part of one circuit pattern discriminated different from the other circuit pattern is detected as a defect. To meet the requirement of circuit pattern defect inspection calling for high speeds, a circuit pattern comparison circuit incorporated in the above example is arranged to be capable of comparing two circuit patterns with each other at a rate synchronizing with that of an imaging device or a pattern detector. More precisely, the above-quoted example comprises a logic circuit called a pipeline processing circuit with many shift registers involved.